Myelin from human central nervous system has been obtained in a highly purified form. Protein kinase activity was extracted from myelin with buffers containing 0.15% Triton X-100. Thus far, over the crude extract, a number of chromatographic procedures have allowed only a ten fold enrichment in the specific activity of the kinase. The elution behavior of this enzyme from DE-52 column resembles that of cAMP-stimulated protein kinases which have been classified as Type II. However, the enzyme solubilized from human myelin is only modestly stimulated by cAMP. Therefore, additional experiments are in progress to determine whether it is cAMP-dependent protein kinase.